I have asked dozens of astronauts what it feels like to blast off, and words always fail them. A roller coaster is the standard analogy, with adjectives piled on to suggest that it’s something more thrilling and terrible, something inexpressible. Often their eyes clamp shut at the memory and sometimes they shiver. No one has ever answered with a smile.

When Endeavour blasts off this month, it could well be the shuttle’s last launch (another launch, of Atlantis, is scheduled for June 28, but it has not yet been funded). The end has been a long time coming. The generation of pioneers that conceived and designed the shuttle retired triumphantly decades ago, when outer space still beckoned Americans to another frontier. Emboldened by our flags and boot prints on the moon, we had plans for other planets and stars in our sights. And the shuttle would take us there. The least sexy spaceship ever imagined, it was never intended to be more than a cosmic truck capable of reliably delivering big payloads to low earth orbit at a reasonable cost, a service vehicle for grander dreams. But those visions—of men going to Mars and deep space—have not come true, and after thirty years of shuttle missions, the romance is gone, replaced by real-life experience of the cold, hard void. The fleet will soon be retired without having delivered what we had hoped to see by now: human beings on extraterrestrial trajectories.

Still, there were other dreams. Not so grandiose, perhaps, but meaningful nonetheless, human dreams that the shuttle made possible. Gathered together they form a legacy for the old space bus that enriches our vision of what is possible, which counts as serious progress to my way of thinking. And I am a hard-core space dreamer.

I’ve spent years hanging out at the Johnson Space Center ( JSC). I was usually credentialed as a journalist and filmmaker, but it was really the spirit of the place, that determination to boldly go, that drew me. I was there the day in April 1981 when Columbia was launched from the Kennedy Space Center on the inaugural voyage of the new Space Transportation System ( STS-1). Back then the center had closed-circuit TV with monitors everywhere, and we all watched rapturously as the revolutionary spaceship took off like a rocket and came home like a plane. I still have the mission patch; that’s the kind of space dork I am.

That same Columbia, of course, disintegrated during reentry from its twenty-eighth flight into space in 2003, killing all seven crew members. One of them was Willie McCool, a Lubbockite I’d met a few times. I’ve talked to a lot of astronauts over the years, and I always make a point of asking them about the music they’ve taken on their voyages. McCool brought John Lennon’s “Imagine” and played it over the radio from orbit, sending it down to the rest of us.

The commander of STS-1 was John Young, a legendary spaceman even then. He’d already been an astronaut for twenty years when he took Columbia on its shakedown mission, having made two flights in the two-man Gemini capsule—including the first manned mission in that mid-sixties series—and gone twice to the moon on Apollo. He was among the few Apollo veterans who stayed on at the JSC after those high-flying glory days, a living link to the Right Stuff cowboys of yesteryear and the role model for the other, very different astronauts who would fly on the shuttle.

The shuttle, you understand, represented a new mission. Conceived from the start as a mass-transit vehicle—as opposed to the exploratory spacecraft that preceded it— STS would democratize the new frontier by carrying diversity into orbit. Young was the head of the Astronaut Office in 1978 when NASA selected its first group of new astronauts in almost a decade, a 35-member class that included the first female, Jewish American, African American, and Asian American to go into space and collectively presented for the first time an astronaut face that began to resemble the nation’s. Four of them would die on Challenger eight years later.

More than 350 people have now gone into space on the 133 space shuttle missions, and they represent our species probably better than we deserve. There have been female commanders and farmworker’s sons, schoolteachers, heart surgeons, senators, astronomers, biologists, geologists, psychologists, jet pilots, and enough engineers to construct a space station the size of a shopping mall. And that’s just the Americans. The shuttle also made it possible to internationalize space travel. As Columbia’s commander again on STS-9, Young welcomed aboard Ulf Merbold, a German physicist who was the first foreign national to hitch a ride with an American crew. He was followed over the years by the citizens of fifteen other countries, from Mexico and Switzerland to Israel, Japan, and Saudi Arabia, men and women who took salsa music and sashimi into outer space and gave other cultures a taste of the dream.

Not everyone made it home. A shuttle stack on the launchpad is mostly a gigantic fuel tank with a pair of 650-ton Roman candles bolted to it. When it all explodes according to plan, it’s fantastic to see from a safe distance. I was watching on a monitor in Building 8 at the JSC, just across the campus from Mission Control, during the countdown for Challenger’s tenth launch, in January 1986. Like the NASA employees watching with me, I knew some of the crew members, and I was excited for them, even a little envious.

I remember Ron McNair the best from that crew, because of the saxophone he was taking along. He was planning to play a part in composer Jean Michel Jarre’s massive outdoor concert Rendez-vous Houston, serenading the earth live from outer space. That’s the sort of dream the shuttle encouraged.

The Challenger disaster was a watershed event in self-awareness for both NASA and the nation, a realization of the stakes involved in this particular adventure.